1. Field of the Invention
The present invention relates to a laser treatment apparatus for treating an affected area of a patient by irradiating the affected area with a treatment laser beam emitted from a laser source.
2. Description of Related Art
As one of laser treatment apparatus in the ophthalmic field, a YAG laser apparatus has been known. This YAG laser apparatus is used for incising the posterior capsule of a patient's eye to treat after cataract, ripping (or cutting) the vitreous fibers of a patient's eye to treat traction retinal detachment, and so on.
In general, when an operator operates a laser apparatus to irradiate an affected area of a patient to be treated with a treatment laser beam, the operator adjusts the focus of the laser apparatus on the affected area while observing a visible aiming light made coaxial with the treatment laser beam. As an aiming manner of the YAG laser apparatus, there is known a manner of separating (or dividing) aiming light into two luminous flux which will pass on opposite sides of an optical axis of a treatment laser beam, and then overlapping the two luminous flux one another at an aiming point on an affected area (so as to focus on the same position) thereby to facilitate the aiming in a focusing direction. In such the apparatus using the above aiming manner, one fixedly divides the aiming light into two luminous flux in a vertical (i.e., longitudinal) direction or a horizontal (i.e., lateral) direction with respect to an eye to be treated, and another is provided with a rotary function of automatically rotating the aiming light in order to check the overlapping state of the two aiming light beams overlapped one another at one point.
Meanwhile, in the case of posterior capsule incision, the posterior capsule is clouded, which easily reflects the aiming light, so that each position of the two divided aiming light beams can be clearly observed. Accordingly, overlapping the divided aiming light beams at a point is not much difficult. At this time, it is very convenient to automatically rotate the aiming light beams for the purpose of confirming the overlapping state of the aiming light beams.
However, when cutting of the vitreous fibers for traction retinal detachment treatment is carried out, normal portions of the vitreous fibers being transparent, the positions of the aiming light beams are very hard to observe unless the aiming light beams properly fall on the clouded vitreous fibers that pull the retina. Accordingly, in the case where the divisional direction of the aiming light beams differs from the extending direction of the vitreous fibers in the area to be cut, both of the two aiming light beams can not be observed at the same time. When only one of the aiming light beams is observable, it is difficult to determine whether the aiming light beams are overlapped one another (which means that the aiming light beams come into focus at the same point) or only one of the two aiming light beams is viewed. Therefore, it takes a much time to confirm aiming propriety and perform proper aiming (alignment). Alternatively, when the vitreous fibers are cut with the apparatus having the automatic rotating function of aiming light, similarly, fine adjustment is hard and the positions of the aiming light beams can not be confirmed. This may require a long time for conducting proper aiming (alignment) of the apparatus to the affected area of a patient.